Hot Spot (cricket)
Hot Spot is an infra-red imaging system used in cricket to determine whether the ball has struck the batsman, bat or pad. Hot Spot requires two infra-red cameras on opposite sides of the ground above the field of play that are continuously recording an image. Any suspected snick or bat/pad event can be verified by examining the infrared image, which usually shows a bright spot where contact friction from the ball has elevated the local temperature. Where referrals to an off-field third umpire are permitted, the technology is used to enhance the on-field umpire's decision-making accuracy. Where referrals are not permitted, the technology is used primarily as an analysis aid for televised coverage.
Its principal application in cricket is in deciding whether the ball has struck the batsman's bat or pad – this determination being critical in determining if a batsman is out or not on appeal for LBW or caught.
In considering whether a batsman is out when the ball strikes bat then caught by a member of the fielding team or caught in front of the stumps when ball hits pad, one of the most difficult decisions is whether the ball struck the pad only, or the bat only, or (if it struck both) whether the pad or the bat was struck first. If the ball strikes the bat only, or strikes the bat followed by the pad, then the batsman could be out caught but not LBW. If the ball strikes the pad in front of the stumps or inline with stumps, then the batsman could be out LBW but not caught. If the ball strikes the pad followed by the bat, then the batsman could be out LBW or out caught if a fielder catches the ball. The batsman's bat and pad are often close together, and it can be very hard to determine by eye which was struck first, whereas the hotspot technology can often resolve the question.
Hot-spot imagery is also used to show which part of the cricket bat hit the ball, as ideally the batsmen try to "middle" the ball i.e. hit it where the sweet spot lies. Hot spot camera provides some valuable information while analysing the strokes played by a batsman.
Hot Spot uses two infra-red cameras positioned at either end of the ground. These cameras sense and measure heat from friction generated by a collision, such as ball on pad, ball on bat, ball on ground or ball on glove. Using a subtraction technique a series of black-and-white negative frames is generated into a computer, precisely localising the ball's point of contact.
Hot Spot uses technology developed in the military for tank and jet fighter tracking. The technology was founded by French scientist Nicholas Bion, before being worked upon by many companies in Paris and being bought and adopted by the Australian Nine Network.
The ICC announced that Hot Spot images would be available for use as part of its ongoing technology trial during the second and third Tests (March 2009) in South Africa. The system was to be available to the third umpire in the event of a player referral.
For the 2012 season BBG Sport introduced a new generation of HOT Spot using the very high performance SLX-Hawk thermal imaging cameras provided by UK based Selex ES. These cameras provided sharper images with improved sensitivity and much less motion blur than earlier HOT Spot technologies. As a result, the latest HOT Spot system is able to detect much finer edge nicks than in previous seasons, essentially ending all earlier doubts about the capability of the technology. Following the success of this updated HOT Spot system, BBG Sport and SELEX Galileo (than Selex ES, in turn merged in Leonardo-Finmeccanica since 2016) signed an exclusivity agreement for the supply of SLX-Hawk cameras for HOT Spot in cricket and other sports.
Ultra-edge is termed as Hot Spot's enhanced version of Snickometer.  When the ball has hit the batsman's pads, Ultra Edge creates four frames and automatically uses all the frames to give precise result. It is able to differentiate more clearly over sounds created by bat, pads or clothing. Ultra Edge was introduced in 2016, as a better option to Snickometer.
Hot Spot has two main advantages over its competing technology, the Snickometer, which is a sound-detection based system. Snickometer often produces inconclusive results indicating contact (potentially any combination of bat, pad and ball) only, whereas the Hot Spot clearly shows exactly what the ball strikes. Precise synchronisation of the Snickometer sound with associated pictures takes time, making it currently not suitable for use in the umpire decision review system.
Hot Spot technology, even though claimed to be extremely accurate, is not used in many matches. The main reason for this is its expense: $6000 per day for the use of two cameras and $10000 for the use of four cameras. Warren Brennan, the owner of BBG Sports, said the unwillingness of the International Cricket Council or national cricket boards to pay to use the expensive technology had restricted its use: "We won't be supplying Hot Spot to the World Cup next year, even for the semis or finals, if the cricket boards want a feed of that for adjudication purposes, they should contribute to the costs. The Ashes could be the last hurrah."
In the India-England ODI Series in 2011, there were controversial decisions based on the Hot Spot technology going against India's Rahul Dravid on more than one occasion where Hot Spot replays proved inconclusive and yet Dravid was given out. On one occasion, there seemed to be a nick which Hot Spot wasn't able to detect. These incidents threw the role of Hot Spot technology into doubt once again.
In the 2013 Ashes, many decisions again cast doubts on Hotspot Technology.
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